Compressor suction valve



May 9, 1950 TRASK 2,506,751

COMPRESSOR SUCTION VALVE Fil ed NOV. 3, 1945 2 Sheets-Sheet 1 May 9, 1950 A A TRASK 2,506,751

COMPRESSOR SUCTION VALVE Filed Nov. 5. 1945 2 Sheets-Sheet 2 i y/Z 7 1/5.

the valve member as comprises a relatively thin disc-like member that is normally dished as shown in Fig. 4 so as to be concave on one face thereof. A plurality of openings or ports 37 pass through'the disc and the relative locations of these ports 3? with respect to the center of'the disc likewise may be varied as will be disclosed hereinafter. The disc 3t is flexible so that it may readily assume a flat condition as shown for example in Fig. 3, but the characteristic of the material in the disc is such that the valve 30 will normally assume the dished position shown in Fig. 4.

A number of different variations or embodie merits of the invention are illustrated herein, but in all of them the valve 30 when properly mounted on the piston head 28 is disposed with its concave side facing the piston head. This condition is illustrated in Figs. 6, and 12 and in each instance the relationship of the various elements corresponds to the at-rest position of the piston 26. On acceleration of the piston durin the suction stroke thereof the valve member is caused to flatten out as shown in Figs. 7 and 13, in. which position the valve member 30 is held underneath the shoulder portions of the valve button 33 in spaced relationship with respect to the outer surface of the piston head 28. During this suction stroke of the piston 26 it is moving in a. downwardly direction in connection with Figs. '7 and 13 or in a direction from left to right in connection with the showing of Fig. 1.

During the acceleration phase of the compression stroke the valve member as assumes the flat condition shown in Figs. 8 and 14 wherein the valve member is seated against the valve seat 29 formed on the outer surface of the piston head 28.

Referring particularly to Fig. 6 the valve 30 in this embodiment of the invention is shown in its normal position of rest on its valve seat on the head of the piston 26. In this form the flanged head of the button 33 holds the valve member 30 in tension between the shoulder of the button 33 and the valve seat on the end of the piston head 28. In this position the periphery of the concave face of valve member 55 is urged by spring action of the valve member against the valve seat. When the piston is placed in operation and during the initial stages of acceleration of the piston the valve member 30 remains in its at-rest position shown in Fig. 6 until the rate of reciprocation of the piston 28 is increased sufficiently to cause flexing of the valve member 39. During this reciprocating motion ofvthe piston 26 the fluid in the cylinder 26 passes through the open ports 36 and 3'1 located respectively in the piston head 28 and the valve member 30. When a predetermined reciprocating speed of the piston 26 has been reached the pressure of the fluid against the concave side of the valve member 30, together with the influence or" its own inertia on acceleration during the suction stroke of the piston causes the valve member to assume a flattened position in spaced relationship with respect to the valve seating as shown in Fig. '7. Under these conditions the fluid in the cylinder flows into the compression chamber of the cylinder from the interior of the piston through ports 36 and 31. At the end of the suction stroke the forces applied to the valve member 33 are released so that the valve member returns to its at-rest position shown in Fig. 6. During the ac celeration phase of the compression stroke of the piston the fluid taken into the compression chamher which is now located on the outside of the valve 30, causes the valve member 3!; to assume its flat position shown in Fig. 8 against the valve seat. In this flattened or closed position of valve to the ports 36 and 37 are out of alignment and completely closed ofi :so that the fluid in the compression chamber is forced out of the cylindeithrough port 22 (Fig. 1) and past the reed or flap 24.

In the arrangement shown in Fig. 6 the ports 3'! in the dished valve member 30 are disposed adjacent to the center of the valve member 30, whereas the ports 36 in the valve head 28 are disposed at remote positions with respect to the center of the valve head. Under these conditions the spherical curvature or dished shaped condition of the valve-memberit creates an arched passage for communication between ports 36 and 3? during all the time that valve member 30 retains its dished shaped condition. When the valve member 36 is in its flat open position shown in Fig. 7, additional openings are provided around the edges ofthe valve to provide freer flow of the fluid from inside the piston 26 to the compression side of the cylinder. The annular groove 35 in the valve seat 29 increases the cross sectional area of communication from ports 36 to the annular opening provided under the periphery of the valve member 39 while the valve is in its open position shown in Fig. 7. Thus valve member 39 provides a proportionately large suction opening and thereby high volumetric eificiency is obtained at high speeds of compression operation. This is one important feature of the present invention.

The preloading of spring tensioning under valve button 33, tending to maintain its spherical curvature in opposition to its force of inertia and to the fluid resistance, gains three important functional results. In the first place, by means of this tension, the beginning of valve functioning when the compressor is first started may be delayed to any one of a wide range of speeds. The specific speed of operation will depend upon the amount of spring tension in the valve 30, and the greater this tension, the higher the speed at which the compression will begin. In the second place, the beginning of compression is definite and critical to the speed of reciprocation. The valve will remain completely inoperative up to a predetermined'speed and will then begin to function fully when a small increase of compressor speed is added. 7

In a compressor having a normal speed of 1725 R. 'P. M. for example, valve as may be designed to remain inoperative and thereby to keep the compressor unloaded during the period when the compressor is started from rest and is accelerated up to-a speed of 300 R. P. M. At 325 R. P. M. the compressor will function to cause compression. 7

The third importantfunctional result gained bypreloading the valve 35} with spring tension is;the preventing of suction valve flutter during all parts of the pumping cycle.

{it theend of the suction stroke, valve 36 regains itsnormal position of rest as shown in Fig. 6 and remains unseated in this dished condition during the first part of the compression stroke. The seating of valve 35 takes place when acceleration of the piston 26 is suflicient to cause the inertia of the valve to equal its spring tend:

ency to retain the spherical curvature which holds the valve off its seat. The forces that overcome this spring tendency result from the combined. influence. of the inertia of the valve 30 in diameter is made asters;

and the -pressureof the. fluid "being compressed.

"when a valveis designed to meet the selected loading speed, a ratio oi valve thicknessto. spheriioalcurvature is selected. to produce an inertia= tension'balance in thevalve at the speed it is desired to have compression started. For ex: ample: Ina compressor operated at 17.50 R. P. M. and having a piston diameter of 1% it isdesired to start compression at 30.0 R. P. M. A valve from fiat spring valve steel .016- in thickness and dished toa spherical curvature having theseating surface of thevalve next tov its central hole .012 higher than the plane of its periphery. Under valve button 33 the valve is compressed .002" lift-from its seat adjacent to the valve button is .010.

Valves constructed in accordance with this invention will deliver improved volumetric efficiency at; high speeds because such valves allow a greator volume of fluid to enter the compression chamber during the suction ortion of the pumping cycle than is allowed by the conventional suction vaives, which are given an inherent tendency to remain seated in opposition to the fluid flow ioroing the valve open by means of fluid pressure. The unseated valve construction of this invention permits an increased fluid volume to be adniitted to compression because the valve is constructed so that it will open sooner and close later than the conventional valves that are retained hat on their seats in their normal at-rest position.

at the end of a compression stroke, which is of course the beginning of a suction stroke of the pisto 26, th v 0 w l be orened by the s rin ension which normally holds the valve 30 in its'dished condition before a fluid pressure and flow is induced that would otherwise open h valve a a lt po t du in h v p mpifig cycle. This earlier opening of the valve will allow'a larger volume of fluid to reach the compression chamber to be pumped thereby resulting an improved volumetric efiioiency.

At theend of the suction stroke of the piston 25. the valve 36 will be held open by the springv tension until forces, resulting from fluid flow and valve. inertia induced by the compression stroke cause the valve to close. Thus valve 3& closes only sometime after the beginning of the commt-sss on st oke- S h v l must e for ed {nosed against its spring tension, it will remain, open longer than in the'case of: the conventional suction valves that are retained on their seats by tension. The lag in the seating of valve induced 30 takes advantage of the inertia of the fluid inrush to the compression chamber by providing time to include the last of the inlet flow induced y h rtia o the fluid t e r- In high speed gasoline engines it is common practiceto open the intake valves before the piston; has reached the position corresponding to upper dead center and to close the valves many degrees of angular rotation after the end of the intakestroke. This timing permits faster engine speeds than could be attained with the use of aishortertimed intake stroke, because the increased time admits an increased charge that obviously contains more latent energy. Likewise the efficiency of a compressor employing a valve oi thisinv e ntion, is increased because the normally open suction valve increases the time and length in angular degrees of the suction portion of the pumping cycle. More fluid enters the compression chamber during each suction stroke,

so that its normal e such that the valve will flex 75 the valves in the first two embodiments.

bodiment shown in 6 more; fluid is coirlpressed,- and an improved v umetric efficiency is: gained.

The weight tension ratio of valve 30 may he in opening andin assuming a fiat position on the valve seat; 29 under the influence of its own inertia. Valves of the type described will function independently, of fluid flow and will pump. a high vacuum when callednpon to do so. When a, high density fluid, such as. Freon is pumped at pressures: above atmospheric pressures, then valve 39 may be constructed to have a stronger tension adapted to resist both the forces of inertia and fluid. flow which forces flatten out the valve on its seat 29 during the compression stroke. Though the valve is simple, it effects a complicated and exact, coordination of many factors that become re.-. solved into a definite ratio of thickness to. di-' ameter and amount of spherical curvature :for each combination of loading speed, normal rune ning speed and fluid density in a high speed pump.

A different embodiment of the invention is shown in Fig. 10 wherein all the various elements are the same as those shown in Figs. 1 toting clusive, except that the height of the shank-3% on the button 33 is greater than in the previous embodiment. In other words, when the valve 30 is in its at-rest position as shown in Fig. 10. there is a space between the shoulder on the head of the button 33 and the valve 30-. This extra space permits the valve 33 to move freely above its seat in a direction away from the valve seat without the valve 39 being flexed to a .flat condition.

Valve -30 in this embodiment of the invention functions substantially in the same. manner as previously described with respect tOthGl'fiI'SbfiIH: bodiment. The functional difference is'in. the realization of a higher lift of" the valve-from the seat of the suction stroke resulting in, advan: tages in vacuum pumps. and compressors sup; plied w'th fluids at low absolute pressures. Valves arranged in accordance with the cm:

Fig. 10 will pump and control fluids at very low density and pressure with verygood volumetric efficiency and will create higher vacuum than can be obtained by con..- ventional compressor suction valves.

The third embodiment of the invention is shown in Figs. 11 to 14 inclusive. In this ems bodiment the elements making up the entire as? sembly-are similar to the first embodiment of the invention except for the relative location of the fluid intake ports 35 and 31- respectively in the head 28 of the piston 25 and in the valve 311; In this instance the ports in the valve .30. are shown at 3111 in Fig. 11 and are disposed adjacent to the outerper-iphery of the valve. The piston head 28 as shown. in. Fig. 12 is provided with its ports shown at 36c disposed adjacent to the center of the headandthe annular groove indicated at 35a has a diameter less than that of the groove 35 shown in Fig. 1. In this third embodiment of the invention, the valve button 33 holds the valve 30 under a slight tension on its seat as is. the case in connection with the first embodiment of the invention. If desired, of course, the valve button 33 may allowlimited vertical clearance as in the caseof the embodi ment shown in Fig. 10.

Suction valves of the type shown in Figs. 11 to 14 inclusive. are adapted for startingv com; pression at lower reciprocating speeds than are As previously mentioned, the valves of all'three embodiments are influenced by their own inertia and by their own fluid. The valve shown in the third embodiment, however, is influenced to a greater degree by the flow of fluid that is being pumped. At the start of compressor oper- I ation during the inertia acceleration phase, fluid flows from the cylinder through ports 37a in the valve 30, through the arched passage between the valve 30 and its seat (Fig. 12) and finally through the piston ports 36a during the compression stroke when the reciprocating speed of the piston 26 is insuiflcient to cause the valve to flatten out against its valve seat. Because the ports 31a are located close to the periphery of the valve 39 and the clearance beneath the ports is limited the flow of fluid is restricted, thus providing a quicker valve seating at which full compression begins. lhe position of ports 31a affects the compressor R. P. M. at which a valve of this type will start compression. The closer the ports 37a are located to the periphery of the valve, the slower will be the required reciprocating speed of the piston at which compression starts. The closer the ports are to the center of the valve 30, the greater the speed required to start compression. When the reciprocating speed of the piston 28 increases to that required to operate the valve 30, the cycle of operation as shown in Figs. 12 to 14 inclusive corresponds precisely with that previously explained with respect to Figs. 6 to 8 inclusive.

Having thus described my invention, I claim:

1. In a suction valve assembly a piston, a substantially flat valve seat on the head of said piston, a resilient suction valve with a spherical curvature adapted to substantially flatten out so as to conform to and engage the valve seat, the concave face of the valve being disposed toward the piston head, means for retaining the valve normally in unseated condition with the center of the valve spaced from the valve seat, and a fluid port in said valve adapted to be closed by said valve seat.

2. In a suction valve assembly a piston, a substantially flat valve seat on the head of said piston, a resilient suction valve with a spherical curvature adapted to substantially flatten out so as to conform to and engage the valve seat, the concave face of the valve being disposed toward the piston head, and means for retaining the valve normally in unseated condition with the center of the valve spaced from the valve seat, the piston having a port extending through the valve seat thereon, and the valve having a port therethrough disposed in staggered relationship with the first mentioned port.

3. In a suction valve assembly a piston, a substantially flat valve seat on the head of said piston, a resilient suction valve with a spherical curvature adapted to substantially flatten out so as to conform to and engage the valve seat, the concave face of the valve being disposed toward the piston head, and means for retaining the valve normally in unseated condition with the center of the valve spaced from the valve seat, the piston having a port extending through the valve seat thereon adjacent to the center of the seat, and the valve having a port therethrough disposed adjacent to the periphery thereof.

4. In a suction valve assembly a piston, a substantially flat valve seat on the head of said piston, a resilient suction valve with a spherical curvature adapted to substantially flatten out so as to conform to and engage the valve seat, the concave face of the valve being disposed toward the piston head, and means for retaining the valve normally in unseated condition with the center of the valve spaced from the valve seat, the piston having a port extending through the valve seat thereon adjacent to its periphery, and the valve having a port therethrough disposed adjacent to the center thereof.

5. In a suction valve assembly a piston, a substantially flat valve seat on the head of said piston, a resilient suction valve with a spherical curvature adapted to substantially flatten out So as to conform to and engage the valveseat, the concave face of the valve being disposed toward the piston head, means for retaining the valve normally in unseated condition with the center of the valve spaced from the valve seat and retaining the periphery of the concave side of said valve in contact with said valve seat while said valve retains its normal spherical curvature, and a fluid port in said valve adapted to be closed by said valve seat.

6. In a suction valve assembly a piston, a substantially flat valve seat on the head of said piston, a resilient suction valve with a spherical curvature adapted to substantially flatten out so as to conform to and engage the valve seat, the concave face of the valve being disposed toward the piston head, means for retaining the valve normally in unseated relationship to its seat and for restraining its movement relative to its seat to allow a limited movement of the concave periphery of the valve away from the seat while said valve retains its normal spherical curvature, and a fluid port in said valve adapted to be closed by said valve seat.

7. In a suction valve assembly a piston, a substantially flat valve seat on the head of said piston, a resilient suction valve with a spherical curvature adapted to substantially flatten out so as to conform to and engage the valve seat, the concave face of the valve being disposed toward the piston head, means for retaining the valve normally in unseated condition with the center of the valve spaced from the valve seat, said retaining means including means for guiding the valve so as to maintain the concave side of said valve in proper relationship with the seat for intermittent seating on said flat valve seat, and a fluid port in said valve adapted to be closed by said valve seat.

ALLEN TPAASK.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS 

